Can this wristband create your own bespoke DNA diet?

For example, you can look at two packets of nuts and check each with the scanner to see which one would be preferable for you. Prof Toumazou demonstrates with two packets of peanuts. “I love the dry roasted ones, but my scanner shows them up as red. The salted ones are green for me.” Delve a little deeper on the app and it explains the decision. Each product you ever scan and all its nutritional details are listed with a green or red tick next to them. On the dry roasted nuts, there is a red tick by salt (2g per 100g). On the salted nuts, the ticks are all green – there is only 1.3g salt per 100g. This has shown up on the professor’s wristband because his DNA has revealed he is likely to be highly affected by excess dietary salt. He looks sad – he’s a big fan of dry roasted but says now he will always choose the salted version instead. Anyway, there’s good news when he flashes his wristband at two chocolate bars. A Mars is off the menu, but Snickers – a favourite – is green to go.

You could say that much of what the band highlights red is obvious – no one ever thought eating Mars bars would lead to weight loss. And at £120, it’s arguable that those who don’t understand nutrition or are shopping on a tight budget while wrangling a bunch of toddlers will be able to afford the dnanudge anyway. Even though they might benefit from its speedy red/green advice. Moreover, some of us remember that the last great proponent of health nudging was one David Cameron PM who set up a ‘nudge unit’ in the Cabinet Office in 2010 – and that didn’t shift the dial on the national attitude to food. Yet that’s not to say this new piece of kit couldn’t be useful. And its inspiration comes from a good place.

Prof Toumazou developed the dnanudge after his son Marcus fell ill at the age of eight in 2000. “Both his kidneys collapsed suddenly,” he explains. The family learnt that Marcus had inherited a genetic predisposition to kidney disease through a renal mutation in his genes. “We couldn’t have prevented it,” says Prof Toumazou, “but – if we had known earlier – we could have managed his lifestyle differently to protect his kidneys longer.” Marcus is now well and the recipient of a donor kidney, but the professor remembers well the feeling of confusion when it happened and what it was like to be thrown into a world of acute medicine as they dealt with home dialysis while he waited for an organ donor. “Our situation inspired the dnanudge,” says Prof Toumazou, “a way to find genetic predispositions and then demystify them for the consumer.”

The dnanudge is not diagnostic, he is at pains to point out. It doesn’t reveal whether a user has cancer or heart disease, but their predisposition. “It gives you a chance not to mess your health up,” he says. So why should this little wristband work when everything else we have thrown at obesity from gastric bands to five-a-day campaigns has failed to halt the national juggernaut of lard?

“This is about behavioural change,” says the professor. “And giving people an informed choice. The best diet is the one you don’t know you are following.” He’s invented one further twist on the app – a green bar which tracks how sedentary you are. “We know that long periods of inactivity are bad for you. So this nudges you to get up every so often and move about.” You can set how often you want the band to remind you to take some steps. But forget to be active and the green bar starts to turn amber. This, in turn, starts to affect what foods the tracker says are green or red. “This puts the whole idea of steps into perspective,” he says.

My own wristband is now alerting me to get moving. It’s only a few short steps to the fridge but my inner me – my DNA – wants me to go further afield and get some proper exercise. It’s about half a mile to the shops and there’s a double incentive now. Who knows what it will let me eat once we get there?